Sunday, January 14, 2007

Water. It is basic to life as we know it. We drink it, bathe in it, cook with it. But left to its own devices, aided by cold temperatures, variable humidity and wind, water crystallizes into amazing shapes. Seen here up close is snow after it sat for a while in such conditions.

Snow falls in many places. To most of us, snow is just part of the background. Something pretty on the trees; something to plow from the roadway, shovel out of the driveway, or ball up and throw at someone. But in nature, the closer we look, the more interesting things get.

Friday, January 12, 2007

Click the image for a larger view.A blanket of fresh snow covers Redmond, Washington in this pre-dawn shot. The shadows on the snow are cast by moonlight. The brightening of the sky is from the pre-dawn glow of the rising sun. Other glows are from artificial light sources. The slight star trail effect is due to the 60 second exposure time.

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Eye Shutter

Frequently people land on this site with search queries like "what part of the eye corresponds to the camera shutter". With a camera, the shutter opens for a very precise amount of time and allows light to hit the film or sensor inside the camera. The closest comparison to that in the eye would be the eyelid that can open and close but its purpose is more analogous to that of the lens cap than the shutter. Shutter mechanisms come in a variety of configurations. More detailed information about camera shutters can be found in this article [Wikipedia].

Camera lenses also have a diaphragm iris [Wikipedia] which adjusts to increase or decrease the amount of the available light that can pass through it during any given period of time. This corresponds directly to the iris in the eye [Wikipedia] which serves the same purpose. I suspect many people confuse this with the diaphragm-type shutter mechanism, however both the eye's iris and that of the camera are visible through the lens while the shutter is generally inside the camera and out of sight. In modern cameras, the iris is usually fully open except at the moment when a picture is taken so it can be seen to move right about the same time as the shutter.